0XYGEN RADICALS AND IRON- AND ASBESTOS-INDUCED CANCER

这项研究的长期目标是研究02的作用 石棉致癌中的自由基和铁。石棉催化了许多 铁的反应和最致癌的形式一样 含有高达36%的铁。这一建议是基于这样的假设 铁是产生02个自由基的罪魁祸首， 导致石棉生物效应的DNA。铁催化 反应可能会产生H202，通过Fenton反应产生.oh 靶细胞和细胞外H202，通过激活释放 巨噬细胞，可能会增加靶细胞中的浓度以刺激 Fenton反应和.oh的形成。具体目标是：1) 确定添加H202对产品质量的影响 青石棉诱导的体外DNA损伤；2)测定青石棉对DNA损伤的影响 添加胞外H202对DNA损伤量、细胞毒作用的影响 和青石棉处理的SHE细胞的转化；3)测定 抑制细胞生长的化学物质丁硫氨酸亚磺胺的作用 H202的破坏，对DNA损伤量、细胞毒性和 青石棉处理前后SHE细胞的转化 添加胞外H202；4)确定铁的耗竭是否 青石棉对SHE细胞·OH和DNA碱基损伤量的影响 在添加或不添加胞外H202的情况下；以及5)确定 自由基清除剂对DNA损伤量、细胞毒性、 青石棉处理的SHE细胞经青石棉处理前后的转化 添加胞外H202。我们将研究两种类型的DNA损伤， DNA单链断裂(使用Phi x174 RFI DNA体外或原位缺口 细胞内翻译)和DNA碱基损伤(GC/MS-SIM)。.oh的角色 将通过使用特定的自由基清除剂(水杨酸盐， DMSO、二甲基硫脲)。在细胞培养中.OH的形成将是 用水杨酸定量。丁硫氨酸亚磺胺将用于 确定细胞内H202水平升高的影响。

The long term objective of this research is to investigate the role of 02 radicals and iron in asbestos-induced cancer. Asbestos catalyzes many of the same reactions that iron does and the most carcinogenic forms can contain as much as 36% iron. This proposal is based upon the hypothesis that iron is responsible for the generation of 02 radicals that damage DNA resulting in the biological effects of asbestos. Iron-catalyzed reactions may generate H202 to produce .OH via the Fenton reaction within the target cell, and extracellular H202, released by activated macrophages, may increase concentrations in the target cell to stimulate the Fenton reaction and formation of .OH. The specific aims are: 1) determine the effect of H202 addition on the quantity of crocidolite-induced DNA damage in vitro; 2) determine the effect of addition of extracellular H202 on the amount of DNA damage, cytotoxicity and transformation in crocidolite-treated SHE cells; 3) determine the effect of buthionine sulfoximine, a chemical that inhibits cellular destruction of H202, on the amount of DNA damage, cytotoxicity, and transformation in crocidolite-treated SHE cells with or without the addition of extracellular H202; 4) determine if iron-depletion of crocidolite affects the amount of .OH and DNA base damage in SHE cells with or without the addition of extracellular H202; and 5) determine the effect of radical scavengers on the amount of DNA damage, cytotoxicity, and transformation in crocidolite-treated SHE cells with or without the addition of extracellular H202. Two types of DNA damage will be studied, DNA single strand breaks (using phi X174 RFI DNA in vitro or in situ nick translation in cells) and DNA base damage (GC/MS-SIM). The role of .OH will be investigated by using specific radical scavengers (salicylate, DMSO, dimethylthiourea). The formation of .OH in cell cultures will be quantified using salicylate. Buthionine sulfoximine will be used to determine the effects of increased intracellular levels of H202.